Target devices for characterizing terahertz imaging systems are provided. The target devices include a terahertz resolution pattern having spatially distributed resolution features and one or more prism assemblies configured to provide a variable contrast level within the resolution features when used with terahertz radiation. Each prism assembly includes first and second prisms arranged in a Frustrated Total Internal Reflection (FTIR) configuration.

Methods for design and production of highly sensitive active and passive light detecting devices and systems. Orders of magnitude improvement in optical signal detection is made possible in high noise or low contrast scenes. The current invention creates a small spectral difference between two parts of a split light stream. When recombined, the altered light streams partially correlate, and that generates full amplitude signal oscillation at a frequency that depends on the constituent spectrum. The full amplitude signals and spectrum dependent oscillation make signal discrimination much better than intensity-only methods. The effect of read noise, amplifier noise, dark current noise, and thermal noise due to photo detector shunt resistance, become less important when compared to light detection using prior art methods

A system for correcting the wavefront of a laser beam includes a beamsplitter for splitting off a fraction of the laser beam to be used as a diagnostic beam, a focusing element for bringing the diagnostic beam to a focus, a measurement subsystem for measuring sizes of the diagnostic beam at upstream and/or downstream locations with respect to a nominal location of the focus, and at least one adaptive optic, located upstream from the beamsplitter, for correcting the wavefront of the laser beam at least partly based on the measured sizes of the diagnostic beam at the upstream and/or downstream locations. The upstream and downstream locations correspond to mid-field locations in the laser beam as imaged by the focusing element. The system takes advantage of the sensitivity of the laser beam size to a waist location shift being greatest at one Rayleigh length from the nominal waist location.

An optical inspection system includes a brightness inspection module for inspecting the brightness of a light emitting element, an integrated inspection module for inspecting the near field optical characteristic and the beam quality factor of the light emitting element, and a far field inspection module for inspecting the far field optical characteristic of the light emitting element. As a result, the optical inspection system is space-saving and capable of reducing the distance and time of the movement of the device under test.

An optical filter including a base member having a layer containing near-infrared absorbing fine particles and a dielectric multilayer film, the optical filter satisfying a requirement that, in a wavelength range of 400 nm to 650 nm, an average of transmittance of any of light incident from a direction perpendicular to the optical filter, light obliquely incident at an angle of 30 degrees, and light obliquely incident at an angle of 60 degrees is 45% or higher and lower than 85%; and a requirement that, in a wavelength range of 800 nm to 1,200 nm, an average of optical density (OD value) of any of light incident from the direction perpendicular to the optical filter, light obliquely incident at an angle of 30 degrees with respect to the perpendicular direction, and light obliquely incident at an angle of 60 degrees with respect to the perpendicular direction is 1.7 or higher.

Aspects of embodiments pertain to a sensing systems configured to receive scene electromagnetic (EM) radiation comprising a first wavelength (WL1) range and a second wavelength (WL2) range. The sensing system comprises at least one spectral filter configured to filter the received scene EM radiation to obtain EM radiation in the WL1 range and the WL2 ranges; and a self-adaptive electromagnetic (EM) energy attenuating structure. The self-adaptive EM energy attenuating structure may comprise material that includes nanosized particles which are configured such that high intensity EM radiation at the WL1 range incident onto a portion of the self-adaptive EM energy attenuating structure causes interband excitation of one or more electron-hole pairs, thereby enabling intraband transition in the portion of the self-adaptive EM energy attenuating structure by EM radiation in the WL2 range.

An optical sensing module, including a frame, a light sensing element, and a diffusion element is provided. The light sensing element is disposed on the frame. The diffusion element is connected to the frame and is disposed above the light sensing element. In a first sensing mode, ambient light passes through the diffusion element before received by the light sensing element to make the optical sensing module to obtain light intensity of the ambient light. In a second sensing mode, the optical sensing module rotates around a first rotation axis to make the light sensing element face a display surface of the display device for receiving image light of the display surface so that the optical sensing module obtains brightness or chromaticity of the display device. A display device having this optical sensing module is also provided.

Methods for design and production of highly sensitive active and passive light detecting devices and systems. Orders of magnitude improvement in optical signal detection is made possible in high noise or low contrast scenes. The current invention creates a small spectral difference between two parts of a split light stream. When recombined, the altered light streams partially correlate, and that generates fall amplitude signal oscillation at a frequency that depends on the constituent spectrum. The full amplitude signals and spectrum dependent oscillation make signal discrimination much better than intensity-only methods. The effect of read noise, amplifier noise, dark current noise, and thermal noise due to photo detector shunt resistance, become less important when compared to light detection using prior art methods.

A lens module (38) is provided that has a module housing (42) having a base (44) and a side wall (46), an adaptive lens (40) variable in its focal length in the module housing (42), and a pressing element (48) to hold the adaptive lens (40) in the module housing (42), The pressing element has a wave spring (48) here.

A single shot autocorrelator for measuring duration of an ultrashort laser pulse in the far field, having a beam splitter to form two beams from an input ultrashort pulse: the reflected beam is firstly reflected by two mirrors mounted on a translation stage for adjusting time delay and subsequently a third mirror, and after focused by a spherical convex lens, enters a naturally grown strontium barium niobate crystal along the crystal z axis; the transmitted beam is firstly focused by a spherical convex lens, and after reflected by two mirrors, enters the crystal along the crystal z axis from opposite direction. The crystal is in the common focal regions of two spherical convex lenses and generates the transverse second harmonic pulse beam that is the autocorrelation signal to be recorded, which is imaged with an optical microscope onto a charge coupled device camera mounted perpendicular to the beams.